Feynman diagrams depicted in Fig. REF (a-d) contribute to the baryon magnetic moment operator, for \(\Delta =0\) , as [1]}, [2]}
\(\delta M_{\textrm {loop 2ad}}^k = \frac{1}{2} \left[A^{ja},\left[A^{jb},M^k \right] \right] \Pi ^{ab}, \) 
